Liquid spraying apparatus



Nov. 19, 1968 5 Sheets-Sheet l Filed Nov. 16, 1966 Nmf VN. .DW N 0% wm ATTORNEYS NQ WQ* me mM @N NY l A N DNN m.\ N W\ mm1 N\W mvOW Nov. 19, 196s C. MANN 3,411,673,

LIQUID SPRAYING APPARATUS Filed Nov. le, 196e r s sheets-sham 2 F'IG-2 I NVEN TOR (S4/P4 MAN/V BYv MMWQM ATToRNEYs- NOV. '19, 1968 C. MANN LIQUID SPRAYING APPARATUS 3 Sheets-Sheet 5 Filed NOV. 16, 1966 NVENTOR CA MA/V/V BY M ATTORNEYS United States Patent O 3,411,673 LIQUID SPRAYING APPARATUS Carl Mann, 1228 Yorkshire, Grosse Pointe Park,

Mich. 48230 Filed Nov. 16, 1966, Ser. No. 594,843 19 Claims. (Cl. 222-189) ABSTRACT OF THE DISCLOSURE lImproved high pressure airless liquid spraying apparatus incorporating several features including a diaphragm operated plunger which senses output line pressure to unload the high pressure pump in response to a predetermined increase in downstream pressure as when the trigger of the spray gun is released to halt spraying. A high volume, low pressure supply pump is also provided which includes a flexible hat-shaped seal which envelopes the impellor of the pump and isolates the same from the abrasive materials such as paint being pumped to the input side of the high pressure pump. The low pressure side of the system also includes a self-cleaning filter. Modifications of the pump unloader are also disclosed which operate as an adjustable pressure regulator. Further details of these and other features will be found in the description.

This invention relates to improvements in liquid spraying apparatus of the airless type wherein liquid is forced under high pressure through a small orifice to produce a spray by hydraulic atomization, and more particularly to improvements in the airless liquid spray apparatus disclosed in my copending application Ser. No. 406,478, filed Oct. 26, 1964, now United States Patent No. 3,317,141.

It is an object of the present invention to provide an improved airless spraying apparatus which: (1) is lightweight and compact so that it is easily hand transportable;

(2) is capable of equal or better performance than preexisting airless spraying equipment but does not require the air compressors, air hoses, air line filters and air pressure regulators of such pre-existing airless equipment; (3) is capable of pumping liquids at high pressures, for example, on the order of 1,500 to 3,000- p.s.i., for subsequent airless spraying of the liquids in a manually controllable and practical fashion; (4) may `be used for interior as well as exterior work in locations where only household electrical outlets are available as a power source; (5) may be powered either by a fractional horsepower electrical motor -or a small internal combustion engine; (6) is capable of withstanding the wearing action of abrasive liquids such as titanium dioxide paint and the like when being pumped at high pressures for sustained periods; (7) is relatively simple and inexpensive in construction and reliable in operation; and (8) not easily susceptible to clogging or jamming by dirt or solid particles entrained in liquid being sprayed.

Further objects of the present invention are to provide improvements in airless spraying equipment which effect:

(9) reduced wear of the valves and valve seats in the high pressure paint pump of the system;

(l0) isolation of the output of the -high pressure pump from the downstream pressure expansion chamber effects of the flexible hose or other conduit system connecting the output of the lpump to the spray gun;

(11) continuous circulation of the paint or other liquid being sprayed to and from the container in a low pressure system at a relatively high volume so as to maintain the paint in a well mixed condition;

(12) the aforementioned 10W pressure continuous circulation in an economical and reliable manner by employing a rotary eccentric pump which contains an improved sealing arrangement for the drive member thereof and which is driven by the same drive shaft which drives the reciprocating piston of the high pressure paint pump of the apparatus;

(13) the supply of filtered paint at low pressure to the inlet of the high pressure pump by a self-washing, clog-free filter arrangement disposed in the low pressure side of the system, thereby further reducing pump wear and clogging problems throughout the high pressure side of the system and isolating the filter itself from the high pressure side of the system;

(14) ready substitution of various types of prime movers for driving the low pressure and high pressure pump mechanisms so that the apparatus may be readily converted for use in explosive atmospheres or for various foreign countries operating on differenty power frequencies and voltages; and

(V15) adjustable regulation of the output pressure of the liquid delivered to the spray nozzle.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of an exemplary embodiment of the invention as shown in the accompanying drawings wherein:

FIG. l is an elevational view of a portable airless paint spraying unit of the present invention with portions thereof shown in vertical center section to illustrate details thereof, and with a spray gun shown semi-schematically on a reduced scale.

FIG. 2 is a fragmentary end elevational view of the left-hand end of the apparatus as viewed in FIG. 1, with portions thereof shown in vertical center section on line 2-2 of FIG. 1 to illustrate details of the low pressure recirculating pump of the present invention.

FIGS. 3 and 4 are fragmentary axial center sections of modified forms of valve unseaters which also serve as output pressure regulators in accordance with the present invention, FIG. 4 further including a schematic showing of a portion of the high pressure diaphragm pump of FIG. 1 with connections to themodied valve unseater and pressure regulator to illustrate a modified form of pump unloading and pressure regulating system also in accordance with the present invention.

Referring in more detail to FIGS. l and 2, the airless liquid spray apparatus of the present invention as exemplied by the illustrated port-able embodiment includes a four-legged base 10 on which is suitably mounted a removable cover 12 for enclosing the various components of the apparatus supported on ybase 10. An electric motor 14 is removably mounted on the horizontal platform 16 of the base and, by way of example, may be a threequa-rter horsepower AC .motor rated at 1,725 r.p.m. and operable on llO-volt AC house current. Suitable disconnectable power leads and on-off switch connections (not shown) are provided for motor 14 to facilitate substitution of various types of motors, such as explosion proof and/or foreign power rated, to meet environmental requirements.

Motor 14 has a `drive shaft 18 which is removably coupled to a crankshaft 20 by an axially split collet 22 externally threaded for engagement with internal threads of a tapered bore 24 in one end of the crankshaft 20. Hexagonal anges 26 and 28 are provided on -collet 22 and on crankshaft 20 respectively so that these two members may be coupled or uncoupled with a pair of wrenches. Collet 22 is slida-bly keyed to shaft 18 as by an internal key 29 received in a keyway in shaft 18. When collet 22 is threaded into bore 24, it is radially compressed so that the same frictionally seizes on shaft 18 to thereby supplement the positive driving key connection between shaft 18 and crankshaft 20. Preferably, the threads of collet 22 and crankshaft are of the proper hand relative to the direction of rotation of motor 14 so that the parts tend to be driven further into threaded engagement by the driving torque transmitted through this coupling, thereby insuring a secure connection between the motor and crankshaft.

Crankshaft 20 is journalled in a rectangular, boxlike crankcase housing 38 by axially spaced roller bearings and 32 disposed respectively in internal bosses 34 and 36 of housing 38. The lower end of housing 38 is closed by a bottom Wall 40 and the upper end by a cover plate 42 removably secured -by bolts 44 to the housing. The hollow interior of housing 38 serves as a reservoir for hydraulic fluid, such as automotive transmission uid, and is normally filled to the level indicated at 46. A reduced diameter extension 48 of crankshaft 20 has a threaded portion adjacent a shoulder 50 of the crankshaft which threadably receives a cylindrical crank 52 eccentrically thereon, these parts being properly threaded so that crank 52 is screwed against shoulder 50 by the driving torque transferred from the crankshaft to the crank. Crank 52 thus rotates with crankshaft 20 and is drivingly coupled through an encircling roller bearing 54 to a connecting rod 56 received on bearing 54. Connecting rod 56 has a bifurcated projection 58 at its lower end which is pivotally connected by a pin 60 to the upper end of a piston 62 which reciprocates in a cylinder 64 of a fitting 66 threadably secured in a fboss 68 of housing 38 and disposed (FIG. 2) with its axis inclined from the vertical. Housing 38 is suitably supported on platform 16, as by legs 70, 71 (FIG. 2), and the externally threaded lower end of fitting 66 projects through and below the platform where it is threaded into a bore 72 in the side of a pump casing 74.

High pressure side 0 f system Casing 74 is part of the high pressure side of the syste-m and has a blind bore 76 therein closed at one end by a wall 78 to form a high pressure pulsing chamber. A flexible resilient tubular diaphragm 80 is inserted closed end first into the open end of bore 76 and has a ange 82 which maintains the exterior surface of the diaphragm radially spaced from the wall of bore 76 and which seats and seals against one end of casing 74. The open end of diaphragm 80 has a reinforcing sleeve 86 received therein, and has a reduced diameter nipple portion 83 threaded into an internally threaded counterbore 88 of casing 84. This arrangement sealably secures the diaphragm in casings 74 and 84 and also seals the connection of these casings.

The hollow interior 90 of diaphragm 80 communicates at its open end with an axial bore 92 of casing 84 to form therewith a high pressure liquid pumping chamber. The end of casing 84 remote from the diaphrag-m threadably receives an inlet fitting 94. A check ball 96 and a ring 98 are disposed in a bore 100 of fitting 94, ring 98 being fixed against a shoulder of an internal flange 102 to serve as a valve seat for ball 96. Both of these parts are preferably made of a hard wear resistant material such as tungsten carbide. Ball 96 is held captive between seat 98 and the open end of bore 100 by a retaining pin 104 and operates as an inlet check valve for the high pressure diaphragm pump 80.

An outlet fitting 106 is screwed into a side opening of casing 84 and contains in a stepped passage 107 thereof an outlet check ball 108, a ring 110 against which ball 108 seats, both preferably made of tungsten carbide, and -a retaining .pin 112. Passage 107 of fitting 106 is connected by a passage 113 of a are connector 116 to a conduit 114 which is secured at one end by a clamp nut 118 to connector 116. The other end of tube 114 is similarly plumbed to an elbow by a clamp nut 122, the other end of elbow 120 being screwed into one end of Ia piston housing 124. A double ended male connector 126 is threadably received at one end in a side opening of housing 124 and plumbed at its other end by a coupling 128 to a high pressure output line 130. Line 130i may be a flexible hose which is connected to a conventional spray gun 131 (FIG. 1) having a usual trigger 133 for operating a discharge valve (not shown) which opens and closes communication between line 130 and an orifice of airless hydraulic atomization spray nozzle 135. In accordance with one improvement feature of the present invention, connector 126 houses a back check valve 134 to isolate line 114- and housing 124 from the effects of expansion and contraction of line 130, connector 126 having a stepped bore 132 in which check ball 134- is loosely retained between a pin 136 and a tungsten carbide ring 138 on which ball 134 seats.

In accordance with another improvement feature of the invention, housing 124 and 94 house a hydraulically actuated mechanism adapted to unseat ball 96 during the idle periods when motor 14 is running but the spray gun discharge valve is closed. Connector 124 has a cylindrical axial bore 140 which extends from elbow 120 to a counter bore 142 at the other end of the fitting which receives with a close fit a cup-shaped piston like diaphragm 144 made of a flexible high strength elastomer material, such as polyurethane. The open end of diaphragm 144 faces elbow 120 and its outwardly domed end wall 146 abuts the shoulder at the junction of bores 142 and 144. One end 148 of a cylindrical plunger 150 slides in ybore 142 to movably support the plunger axially within fitting 94 between cup 144 and ball 96. Plunger 150 has a reduced diameter stem 152 adapted to project with a clearance into the reduced passage defined by flange 102. A compression coil spring 154 en-circles plunger 150, .abutting at one end against ange 102 and at the other end against a washer 156 backed up by portion 148 of plunger 150. Sprmg 154 biases plunger 150 axially toward diaphragm 144 until washer 154 abuts the end face of fitting 124, at which point stem 152 is spaced from ball 96 when in its seated position. Spring 154 is selected to yield, and thereby permit movement of plunger axially to the left (as viewed in FIG. 1) into contact with ball 96 and then topush the same off its seat, in response to a predetermined tiui-d pressure in bore 140 acting on cup wall 146 suicient to flex it so that it contacts end 148 and drives plunger 150 to this unseating position. It is to be noted that diaphragm 144 thus serves both as a diaphragm, and also as a cup seal between the high and low pressure sides of the system due to presure fluid in bore 140 expanding the skirt portion of the diaphragm 144.

Low pressure .ride of system The liquid such as paint to be sprayed is delivered from the receptacle containing the same, such as a paint can (not shown), yby a low pressure pumping system Iwhich includes a low-pressure, high volume pump 160 and a filter unit 216 connected in a recirculation circuit so that the liquid undergoes constant recirculation to and from the container in the low pressure side of the apparatus so long as motor 14 is running. Referring to FIGS. 1 and 2, the low pressure pump 160 comprises a body block 162 in which a pumping chamber 164 is defined by a cylindrical bore 166 (FIG. 2) closed at the opposite ends thereof lby an outer plate 168 and an inner plate 170 (FIG. 1) having a crankshaft aperture 171. Plates 168 and 170 are clamped in assembled relation with body 162 by four bolts 172 which also mount the pump assembly against the end face of housing 38 with the axis of bore 166 coincident with the axis of crankshaft 20.

The pumping mechanism of pump 160 comprises a cylindrical disc 176 (FIG. 2) having a threaded stud 178 extending coaxially therefrom and threadably secured in an eccentric bore 180 (FIG. 1) in end portion 48 of crankshaft 20 so that disc 176 is rotatably driven by shaft 120 and revolves eccentrically Iwithin chamber 164. Disc 176 carries a roller bearing 182 thereon which has its inner race'tixed to disc 176 and its outer race Ihearing against the inner cylindrical wall of a skirt portion 184 of a cup-like seal 186. Seal 186 is closed at one end by a radial wall 188 which is axially spaced from disc 176 yand disposed in sliding contact with the inner wall of plate 168, although wall 188 may alternatively be spaced from plate 168. Seal 186 is open at its other end and has a radially outwardly extending annular flange 190 integrally joined to skirt portion 184 which is received in an lannular recess 192 of plate 170 around the margin of opening 171 thereof. The thickness of flange 190 is greater than the depth of recess 192 so that when pump 160 is clamped against housing 38, plate 170 presses flange 190 tightly against the outer face of housing 38 to thereby form a liquid tight seal therebetween which insures that the paint flowing through pump 160 is not contaminated by oil leakage from the pump in housing 38. Cup seal 186 is prefer-ably made of a flexible material adapted to withstand continuous flex-ure caused by the eccentirc motion imparted to skirt portion 184 relative to fixed flange 190, and for this purpose good results have been obtained with an elastomer such as polyurethane, for example.

The pumping mechanism also includes impeller 194 which has a cylindrical portion 196 (FIG. 2) with -an inside diameter adapted to slip closely onto skirt 184 and an outside diameter smaller than that of bore 166. The axial dimension of impeller 194 is slightly greater than the axial spacing between end plates 168 and 170 so that the end faces of the impeller slide with a sli lht pressure against the respectively adjacent lates. Impe ler 194 has an integral tongue portion 198 which extends radially outwardly from portion 196 for the full axial width thereof. Tongue 198 is slidably received in a mating slot 200 which extends radially in lbody 200 from the axis of rotation of shaft for a depth sufiicient to fully receive tongue 198 therein when portion 196 is moved adjacent to the inlet of slot 200. Tongue 198 is longer than the eccentric throw imparted Iby a disc 176 so that it never is withdrawn from the slot. Tongue 198 thus forms a divider in the pump chamber between an inlet passage 20-2 and .an outlet passage 204 (FIG. 2) which communicate with chamber 164 on opposite sides of tongue 198. Preferably passages 202 and 204 are formed by drilling a, bore through body 162 generally tangential to the intersection of bore 166 and slot 200.

Pump 160 is connected to the source of supply of liquid to be sprayed, such as .a paint can filled with paint, by a suitable -fluid conductor 206 threadably connected by a male fitting 208 to the threaded inlet 202 of body 162. Pump 160 is also connected to a uid conductor, such as a hose 208, by a male fitting 210 threadably secured in the outlet passage 204 of body 162. The other end of hose 208 (FIG. l) is connected by a male inlet fitting 212 to a threaded side port 214 of a casing 218 of filter unit 216 near the upper end thereof. The outlet for filtered liquid from unit 216 comprises a threaded nipple 220` at the lower end of casing 218 which screws into fitting 9'4. The open upper end of casing 220 threadably receives a removable closure stud 222 which has a stem 224 on which the upper end of a cylindrical filter screen 226 is piloted. Screen 226 has a grommet 228 at .its rupper end which is slidably received zwith ,a close lit on stem 224 and which abuts a coil compression spring 230 piloted on stem 224, the screen thus being urged downwardly so that a grommet 232 at its lower end seats against a conical internal shoulder of nipple 220. The outer surface of screen 226 is spaced radially inwardly of the wall bore 234 of casing 218 to provide an axial flow space along the exterior of the screen running from fitting 212 downwardly to an outlet fitting 236 which is screwed into a side port near the lolwer end of casing 218. Fitting 236 is connected to a return line 238 which runs beneath housing 3'8 (FIGS. 1 and 2), thence upwardly alongside pump 160, and thence through the top of cabinet 12, the outlet of return line 238 being adapted for disposition in the paint can or other container for discharging at low pressure spray liquid bypassing the high pressure side of the system.

Operation To operate the above described embodiment of the improved airless liquid spraying system of the present invention, motor 14 is energized from .a suitable source of power, such as a common household llO-volt AC outlet. Considering first the high pressure side of the system, motor 14 is normally operated continuously at a constant speed, for example 1,725 r.p.m. thereby rotating shaft 20 at this speed, and via eccentric 52 and connecting rod 56, reciprocating piston 64 at the same frequency to produce .a pulsating pressure variation in the oil trapped in pulsing chamber 76 of the high pressure casing 74. Contraction of diaphragm 80 caused by the high pressure phase of the pulsation pressurizes paint or other spray liquid in puimpL ing chamber '90, 92, thereby seating inlet check ball 96 and forcinig the paint at high pressure past outlet ball 108, through conduit 114, fitting 120, chamber 140 and past check ball 134 into the output line 130 for discharge fro-m the spray gun 131. Diaphragm 80 expands in the lovw pres- Sure phase of the pressure pulsation cycle, thereby causing a reduced or negative pressure in chamber 90, 92 which seats outlet check 108 and opens inlet check 96 to draw iiltered paint from the interior of filter 226 via nipple 220 and fitting 94. This cycle occurs at the pulsation frequency produced by -motor 14, for example 1,725 cycles per minute, and this system is capable of producing very high output pressures in line on the order of 4,000 p.s.i., and even higher.

When the dischange valve of the spray gun is closed to cease spraying, the pressure in chamber of fitting 124 immediately rises to that available at the pump outlet 113, this pressurre change representing that previously lost due to the pressure drop between outlet 113 and chamber 140 during spraying, normally on the order of 75 p.s.i. This rise in pressure is sufficient to overcolme the bias of spring 154 lon plunger 150 so that the end wall 146 of diaphragm 144 bulges or iiexes against portion 148 and thus drives the plunger toward ball 96 runtil stem` 152 contacts ball 96 and moves the same off its seat. This immediately delpressurizes the high pressure pump, .allowing the paint in chamber 90, 92 to course back and forth past ball 96 between chamber 92 and the interior of casing 2118 via fitting 94. Outlet check ball 108 is immediately seated by the pressure differential created when plunger unseated ball 96, the high pressure liquid in conduit 114 and line 130 thus being trapped between ball 108 and the closed dischange valve of the spray gun. Thus so long as the spray gun is shut 01T, this trapped body of liquid maintains .a constant elevated pressure on piston 144 to hold the inlet check 96 open. When the discharge valve of the spray gun is reopened to resume spraying, the pressure drop between outlet 113 and the spray gun causes a pressure drop in chamber 140 sufiicient to` permit spring 154 to drive plunger 150 yaway from ball 96 until stem 152 is spaced from the seated position of ball 96. Valve ball 96 is thus once again free to open and close in response to the uctuating pressure in the pump chamber 90, 92 and hence diaphragm 80 resumes pumping the paint at high pressure from a low pressure source via filter 216, to the spray gun.

Referring now to the operation of the low pressure side of the system, rotation of crankshaft 20 drives the low pressure rotary eccentric pump =at the same rate as the high presure diaphragm pump, e.g., 1,725 rpm., thereby imparting eccentric rotation to eccentric 176 which, via the encircling bearing 182 and seal 196, imparts an eccentric non-rotary motion to impeller 194 so that it sweeps bore 164 and thereby pumps paint at low pressure from inlet 202 to outlet 204 of the pump body at a relatively Ahigh flow rate. Thfus, so long as motor 14 is running, pump 160 draws paint from the paint can via inlet tube 206 and pumps the same through outlet tube 208 into the upper end of the filter casing 218. The paint flows continuously downwardly in the relatively narrow fiow space between screen 226 and the wall of bore 234 at a high velocity and is discharged from this flow space in bypass relation to the high pressure side via fitting 236 back to the paint can via return line 238. Whenever the high pressure diaphragm pump 80 is conditioned to pump paint at high pressure to the spray gun, i.e., when the trigger valve of the spray gun is opened, filtered paint is drawn into the high pressure pump from the interior of screen 226 via fitting 94, at which time a portion of the unfiltered paint flowing by the exterior of the screen 226 flows radially inwardly through the screen to meet the demand of the high pressure pump.

From the foregoing description, it will now be unders'ood that the present invention provides many improvements in the high pressure airless liquid spraying system as disclosed in my aforesaid copending application. The addition of the valve unseating plunger 150 greatly reduces wear on both the inlet and outlet check balls 96 and 108 and their associated valve seats 98 and 110 since these valves no longer cycle continuously but rather only when the spray liquid is being sprayed from the gun. Moreover, the concurrent unloading of the high pressure pump also reduces wear on diaphragm 80 and in addition reduces the power consumption of motor 14 and the heat developed by the motor. The back and forth circulation of the paint between the chamber 92 and filter casing 218 during the idle period of the spray gun helps prevent clogging in the fitting 94 and also helps dislodge particles from screen 226 so that the same may be carried by the return flow via tube 238 back to the paint can. The check valve 134 isolates any return pressure surges from the output line 130, which in the case of a flexible and long line can be considerable, thereby preventing hunting of the valve unseating mechanism.

The provision of a low pressure side and a high pressure side, with continuous paint circulation through the low pressure system produced by the low pressure high volume pump 160, greatly reduces filter clogging and down time, and considerably extends the useful life of screen 226. The paint flowing rapidly along the exterior surface of the screen 226 produces a constant washing action on the screen so that the same remains clog-free for a much longer period of time. This washing action coninues even when paint is being pumped by the high pressure diaphragm pump 80 for discharge from the spray gun since the output of pump 160 exceeds that of pump 80. The auxiliary low pressure pump 160 thus insures that there is always a supply of paint at the inlet to the high pressure pump, at a slightly elevated pressure, thereby supercharging the high pressure pump and insuring very quick response and practically instantaneous achievement of spray pressure so that a high quality spray pattern is developed upon pulling the trigger of the spray gun. In addition, the conlinuous recirculation of the paint through the low pressure side of the system causes a constant flow of paint in the storage receptacle from which it is being drawn so that the paint is being continuously mixed as long as .motor 14 is running.

The construction of the low pressure pump 160 has been found to be highly desirable for pumping abrasive liquids, both impeller 194 and seal 186 being made of polyurethane elastomer material which has shown little evidence of wear even when operated for extended periods in high abrasive fluids. The hat-shaped seal 186 has been found to successfully withstand the continual flexing between the fiange 192 and skirt 184 thereof and isvery effective in sealing the oil in which the pump drive structure is submerged from the paint pumping chamber of pump 160, a highly critical area in which it would be disastrous if leakage developed. Seal 186 thus makes it possible to utilize the oil contained in housing 38 not only as a reservoir for the pulse chamber of the high pressure pump (to which makeup oil is supplied via piston pas- 8 sage 63 and check ball 65 (FIG. l) as described in more detail in my aforementioned copending application) but also as aa lubricant for bearings 30, 32, 54 and 182.

The quick disconnect coupling 22 facilitates interchanging of various prime movers for the spray apparatus, thereby for example enabling economical conversion to explosion proof motors when spraying in explosive atmospheres, or to motors adapted to meet foreign power frequency standards for export. Moreover, all of the components of the spray syste-rn, with the exception of the intake line 206, return line 238 and output line 130, are located `within the confines of cabinet 12 in a compact arrangement where they are protected from damage in handling the portable equipment. Due to the simplicity of the structure of the low pressure pump 160 and the fact that it is driven from the same crankshaft which operates the high pressure pump, the aforementioned benefits of the low pressure continuous flow self washing filter supply to the high pressure side are obtained at a minimum increase in cost over the system described in my aforesaid copending application.

C ombilzed valve zmseater and pressure regulator Referring to FIG. 3, a modified form of valve unseating mechanism 300 is shown in accordance with the present invention with parts corresponding to those previously described given like reference numerals. Unit 300 includes an inlet fitting 302 which is substituted for fitting 94 and an associated piston fitting 304 which is substituted for fitting 124. Fitting 302 has an axial cylindrical through-bore 306 with an internal shoulder 308 therein backing up seat ring 98. Filter unit 216 is theradably mounted in a side port of fitting 302 for communication with bore 306. A plunger 312 yis disposed for axial movement in bore 306 and has a reduced diameter stem portion 314 adapted for engagement with ball 96 in the -manner of plunger 150. Plunger 312 has an enlarged diameter guide portion 316 which carries a pair of O-ring seals 318 adapted to slidably and sealably mount the plunger in bore 306. The right hand end (as viewed in FIG. 3) of plunger 312 is also enlarged to provide a guide portion 320 for the plunger. The shank 322 of plunger 312 between guide portions 316 and 320 is slightly reduced in diameter and is cross drilled to receive a pin 324 the opposite ends of which project through axially extending slots 326 and 328 disposed diametrically opposite one another `in fitting 302. A coil compression spring 330 encircles fitting 302 and abuts at its ends against pin 324 and an adjusting nut 332 is threadably received on fitting 302 to thereby bias plunger 312 away from ball 96.

Fitting 304 has an axial bore 334 which is internally threaded at one end to screw onto nipple 336 of fitting 302, and which receives diaphragm 144 inwardly of the threaded portion with end wall 146 abutting end 320 of the plunger. Bore 334 opens to a smaller counterbore 338 which in turn opens to a still smaller counterbore 340. An internal shoulder 342 in counterbore 340 backs up seat 138 for isolation check ball 134, and output line 130 is secured to the nipple at the right hand end of fitting 304. The high pressure output line 114 is plumbed by a fitting 346 and connector 348 to a side port of fitting 304 for communication with bores 338 and the interior of diaphragm 144. Preferably, a hollow tube 350 has one end thereof inserted with a press fit in counterbore 340 and extends axially with a radial clearance partially into the interior of diaphragm 144 so that liquid flowing into bore 338 from line 114 must flow into the interior of the piston before reaching the outlet line 130, thereby insuring that paint or other material does not collect and deposit Within diaphragm 144 when the passageways are fiushed with water or solvent in a cleanup operation.

The modified valve unseating unit 300 operates to unseat the inlet check ball 96 of the high pressure paint pump in response to diaphragm 144 sensing the full output pressure of the pump "when the discharge. valve of the spray gun is closed in the same manner as the previously described valve unseater 150. However, by providing means such as nut 332 for adjusting the biasing force of spring 330 acting on plunger 312, the pressure required to drive plunger 31,2 to the valve unseating position may be adjusted as desired over a wide range by the operator. In the previous embodiment, spring 154 is selected to permit valve unseating action only at the maximum pressure developed by the pump, which occurs only when discharge from the gun is blocked by closure of the gun trigger valve. With unit 300 the output pressure at the spray gun may be regulated within a wide range as desired by screwing nut '332 to the left (as viewed in FIG. 3) to reduce the spring biasing force so that diaphragm 144 drives plunger 312 to unseat ball 96 in response to a correspondingly reduced liquid pressure in fitting 304. Preferably, spring 330 and nut 332 are designed so that a quarter turn of nut 332 is effective to vary the unseating pressure from a minimum of for example about 500 p.s.i. up to the maximum output pressure capacity of the high pressure diaphragm pump. It has been found that with plunger 3112 so adjusted below maximum pump pressure the same will unseat ball 96 and thereby partially unload the diaphragm paint pump whenever the output pressure exceeds the preselected adjusted value. As soon as the pressure falls in fitting 304 to a point where the fluid force .acting on diaphragm 144 is overbalanced by spring 330, plunger 312 is retracted by spring 330 to permit ball 96 to operate freely in its normal cycle as an inlet check valve, whereupon pu-mp output pressure climbs once more to the pre-set regulated value. This action occurs rapidly, the unloading phase of the cycle being much shorter in duration than the pressure buildup phase of the cycle. Accordingly, unit 300 permits the output pressure to be controlled at a selected maximum value, within relatively narrow limits, which does not alter the spray pattern.

Although the exemplary embodiment shown in FIG. 3 utilizes a spring 330 mounted exteriorly of the plunger casing 302, it is to be understood that an interior spring may also be used as shown in the further modified valve unseater unit illustrated in FIG. 4. In this embodiment a spring 330' is inside a casing 360 interposed between modified `fittings 302 and 304. Spring 330 abuts at one end against an inter-nal pin or flange 324 connected to a modified valve unseating plunger 312' and at the other end against the inner end wall of casing 360. Casing 360 is threadably connected to fittings 302 and 304 as shown in FIG. 4 and is accessible from the exterior of the unit for adjusting the biasing lforce of spring 330 by screwing casing 360 further toward or away from fitting 304. The change to an internal spring arrangement requires an additional seal 362 carried in a groove of casing 360 to seal the counterbore 364 of fitting 302 which receives the male end of casing 360.

FIG. 4 also illustrates a modified automatic pressure unloading system, also in accordance with the present invention, which may be substituted for the 'valve unseating-unloader mechanism 150 of FIG. l and/or the pressure regulator-unloader mechanism of FIG. 3. As illustrated schematically in FIG. 4, the pulse chamber 76 in the high pressure pump casing 74 is connected by a line 370 to nipple 372 of fitting 302. Bore 306 of fitting 302' is connected by a line 374 to the oil reservoir in crankcase housing 38, preferably at a point submerged below fill level 46. Fitting 304 is connected in the same manner as fitting 304 described previously.

With this arrangement, whenever the output pressure of the high pressure pump rises above a predetermined value, determined by the adjustment of the biasing force of spring 330 as set by adjusting casing 360, plunger 312 will be driven by piston 144 toward ball 96 to unseat the same. This opens a return connection from pulse chamber 76 back to the reservoir in housing 38 `via lines 370 and 374, thereby unloading the pulse chamber so that the continuous reciprocation of piston 62 and the associated replenisher valve 65 now pumps oil at low pressure in a recirculation path from housing 38 via piston passage 63, past valve 65, into pulse chamber 76, out line 370, past valve ball 96 into bore 306 and thence via line 374 back to the reservoir in housing 38. Hence the magnitude of the pressure pulsations in chamber 76 is reduced to an insignificant value and consequently diaphragm 80 is essentially relieved of flexing stress. Consequently the paint or other liquid in pump chamber 90, 9,2 is no longer pressurized by diaphragm 80 and therefore the pressure of this liquid drops to the low side pressure at the inlet 220 to the high pressure pump. Hence, valve balls 96 and 108 in the high pressure diaphragm pump cease movement during the unloaded condition which occurs when the discharge valve of spray gun 131 is closed and/or when the pressure in line rises above the maximum regulated value determined by adjustment of casing 360.

The system of FIG. 4 thus can be employedy as the high pressure diaphragm pump unloader in place of plunger of FIG. l to thereby prevent wear of the valve balls during the non-spraying periods, and to prevent excessive pressure build-up in the high pressure side of the system as motor 14 continues to run. In addition, the system of FIG. 4 can be used in place of the adjustable pressure regulator unloader of FIG. I3 to accomplish a regulated output of the high pressure diaphragm pump. By thus unloading pulse chamber 76 to thereby indirectly unload pump chamber 90, 92, an additional advantage is obtained in that oil in the pulse chamber is recirculated during the unloading phase back to the reservoir which serves to cool the pulse chamber and diaphragm 80 by heat transfer from the oil rvia housing 38 to atmosphere. Also, when spraying certain liquid vinyl materials it has been found desirable to minimize turbulence of such material which tends to cause foaming of the same. Therefore the system of FIG. 4 is advantageous in handling such material since it avoids the back and forth surging action obtained with the unloading plunger 150 in the system of FIG. l since diaphragm flexure ceases in the unloaded phase and hence the material in the pump chamber is quiescent in this phase.

I claim:

1. Apparatus for high pressure airless spraying of liquid including in combination a pump having a pump chamber, inlet means connected to said pump chamber and adapted for connection to a source of the liquid to be sprayed. outlet means connected to said pump chamber, inlet and outlet check valve members movably disposed respectively in said inlet means and said outlet means and being cooperable with said pump to cyclically open and close said inlet and outlet means to effect pumping of the spray liquid from said inlet to said outlet means, an output line connected to said outlet means of said pump and pump unloading means including a movable plunger, means for yieldably biasing said plunger toward a first position spaced from the closed position of one of said valve members and movable means exposed to the liquid in said output line downstream from said outlet means of said pump and operably connected to said plunger for biasing said plunger. into engagement with said one valve member to unseat the same in response to a predetermined pressure of said liquid acting on said movable means, said movable means comprising a diaphragm having one side exposed to the liquid in said output line and rigid force transmitting means operably interconnecting the side of said diaphragm opposite said one side thereof with said plunger.

2. The combination set forth in claim 1 wherein said yieldable biasing means includes a spring operably connected to said plunger for biasing said plunger away from said inlet check valve member and means for adjusting the biasing force exerted 4by said spring on said plunger.

3. The combination set forth in claim 2 wherein said plunger has guide means in slidable sealed engagement with said bore intermediate said inlet check valve member and said movable means, a pin secured to said plunger between said guide means and said movable means projecting transversely therefrom exteriorly of the casing, said spring encircling said casing exteriorly thereof and abutting at one end against said pin, and wherein said means for adjusting the biasing force of said spring comprises a rotatable member threadably received on the exterior of said casing and having an operable connection with the other end of said spring.

4. Apparatus for high pressure airless spraying of liquid including in combination a pump having a pump chamber, inlet means connected to said pump chamber and adapted for connection to a source of the liquid to be sprayed, outlet means connected to said pump chamber, inlet and outlet check valve members movably disposed respectively in said inlet means and said outlet means and being cooperable with said pump to cyclically open and close said inlet and outlet means to effect pumping of the spray liquid from said inlet to said outlet means, an output line connected to said outlet means of said pump and pump unloading means including a movable plunger, means for yieldably biasing said plunger toward a rst position spaced from the closed position of one of said valve members and movable means exposed to the liquid in said output line downstream from said outlet means of said pump and operably connected to said plunger for biasing said plunger into engagement with said one valve member to unseat the same in response to a predetermined pressure of said liquid acting on said movable means, said pump unloading means including a casing having a bore therein communicating with said output line downstream of said outlet means of said pump, said movable means comprising a flexible cup-shaped di- 1 aphragm disposed in said bore having one end open and in communication with the liquid in said bore, said diaphragm having a transverse wall closing the other end thereof and a skirt portion integral with said wall, said plunger being disposed in abutting relation with said end wall of said diaphragm whereby the pressure of said liquid acting on said diaphragm from the interior thereof exes said wall to move said plunger toward said inlet check valve `member and said interior pressure also expands the skirt portion of said diaphragm into tight sealing relation with the wall of said bore.

5. Apparatus for spraying liquids under high pressure comprising a prime mover having a rotary output shaft, a crankcase disposed adjacent said prime mover with said shaft extending through said crankcase, a cylinder connected to said crankcase and having a piston reciprocable therein with one end of said piston extending into said crankcase, means operably connecting said shaft to said piston to convert rotary motion of the shaft to reciprocating motion of the piston, high pressure pump means having a pulse chamber, said piston having an end remote from said one end thereof defining a movable wall in said pulse chamber, said high pressure pump means including a diaphragm disposed in said pulse chamber and ow passage means having inlet means and outlet means and inlet and outlet valve associated respectively therewith cooperable with said diaphragm in response to expansion and contraction of said diaphragm produced by fluid pressure pulsations in said pulse chamber to pump liquid from said inlet means to said outlet means, an output line connected to said outlet means adapted for connection to a spray gun, a low pressure pump mounted on said crankcase on the side thereof remote from said prime mover and having an impellor operably connected to said shaft, an input line connected to said low pressure pump, an output line connected to the output of said low pressure pump, a yfilter unit connected between said output line and said inlet means, a return line connected to said lter unit in bypass relation to said inlet means and including a portion disposed for returning the liquid 12 pumped from said low pressure pump to a source of the liquid.

6. The combination set forth in claim 5 wherein said filter unit comprises a casing having a liquid chamber therein, a filter extending within said chamber and having one surface thereof spaced from a wall of said chamber to define a flow space therebetween extending along said one surface of said filter, the surface of said filter opposite said one surface defining with said chamber a filtered liquid space in said chamber, an inlet in said casing communicating with said flow space adjacent one end of said lter and connected to said output line of said low pressure pump, means connecting the filtered liquid space in said chamber to said inlet means of said high pressure pump means, and an outlet in said casing communicating with said flow space at a point spaced axially from said casing inlet, said return line being connected to said casing outlet for conducting unfiltered liquid from said ow space in bypass relation to said inlet means to thereby cause a flow of low pressure liquid along said one surface of said filter to effect a washing action thereof.

7. The combination set forth in claim 6 wherein said low pressure pump is operable to pump the liquid to said lter unit at a rate in excess of the intake rate of said high pressure pump to thereby supercharge said high pressure pump and also effect a continuous washing action on said filter.

8. The combination set forth in claim 6 wherein said low pressure pump comprises a pump body with oppositely disposed sides, a cylindrical bore extending through said body and opening at said sides, a cover plate disposed against one of said sides remote fro-m said crankcase and forming an end wall of said bore, a second cover plate disposed against the other -of said sides between said body and crankcase and having an aperture therein axially aligned with said shaft, inlet and outlet passages communicating with said bore, a slot extending radially in said body from the `axis of said bore, -an impellor ring disposed in said bore with its axially opposite end faces in sliding contact with the respectively adjacent cover plates and having a radial tongue slidably received in said slot, a hat-shaped flexible seal having a cylindrical skirt portion received within said aperture of said second plate and within said impellor ring, an end wall closing one end of said skirt portion and an annular radially outwardly extending flange at the open end of said skirt portion clamped between said second cover plate and said crankcase in sealed relation therewith, an eccentric crank means extending into the open end of said seal and operable for imparting eccentric motion to said skirt portion of said seal to move said impellor in eccentric pumping relation to said inlet and outlet passages.

9. The combination set forth in claim 8 wherein said crankcase has a liquid lubricant reservoir therein, said piston being submerged in said reservoir and having a passage and check valve therein cooperable with said piston for replenishing said pulse chamber with liquid from said reservoir, said crankcase having bearing means in said sides thereof journalling said shaft therein and exposed to the liquid in said reservoir, the interior of said skirt portion of said seal communicating with said reservoir via the adjacent shaft bearing means.

10. The combination set forth in claim 5 wherein said rotary output shaft comprises a disconnectable shaft assembly including a cylindrical shaft directly connected to said prime mover, a crank shaft journalled in said crankcase and having a bore in the end thereof adjacent said prime mover shaft, said prime mover shaft being coaxially received in said bore, a connector sleeve having a through bore slidably received on said prime mover shaft, and means keying said sleeve to said prime mover shaft, said crank shaft bore having internal tapered threads and said connector having external tapered threads mating with said bore threads whereby said connector is slidable on said prime mover shaft into threaded engagement with said bore threads andis radially compressed as the same is screwed into said :bore to thereby frictionally lock on said prime mover shaft to couple the same to said crank shaft.

11. Apparatus for spraying liquid including in combination pump means including a pump chamber, a diaphragm having one side exposed to and forming a movable wall of said pump chamber, inlet means connected to said pump chamber and adapted for connection to a source of the liquid to be sprayed, outlet means connected to said pump chamber, inlet and outlet check valve members disposed respectively in said inlet means and said outlet means and being cooperable with alternating exure of said diaphragm to pump the spray liquid via said inlet and outlet means, a closed pressure chamber filled with liquid and communicating with at least a portion of said diaphragm on a side thereof opposite said one side thereof, pulse means adapted to generate a pulsating pressure on the body of liquid in said pressure chamber to produce said alternating exure of said diaphragm, liquid spray means connected to said outlet means of said pump including an output line, an isolation valve serially connected with said output line adjacent but downstream of said outlet means of said pump, said valve including a valve seat and a movable valve member adapted to close on said seat to block flow from said output line toward said outlet means in response to a reversal of the normal pressure drop in said output line downstream from said outlet means and means responsive to a predetermined pressure in said output line between said outlet means and said isolation valve operable to open one of said valve members.

12. A pump comprising a pump body having a pumping chamber therein, means forming a transverse wall at one end of said pumping chamber, means defining an opening at the other end of said pump chamber axially opposite said one end thereof, means forming inlet and outlet passages communicating with said pumping chamber, an impellor disposed in said pumping chamber and cooperable with said passages to pump uid from said inlet passage to said outlet passage in response to pumping motion of said impellor around the interior of said pumping chamber, a hollow tubular seal member disposed with a first portion thereof extending into driving engagement with said impellor, said seal member having a second portion extending axially through said opening, first means sealing said second portion of said seal member in fixed relation with said pump to said opening, second means disposed adjacent said transverse wall sealing the interior of said seal member from said pumping chamber, said seal member between said first and second portions thereof being iiexible in a plane radially of the axis of said seal member and drive means extending axially within said seal member and having rotor means engaging the interior of said first portion of said seal member to impart said pumping motion to said impellor.

13. The combination set forth in claim 12 wherein said tubular seal member comprises a hat-shaped urethane plastic member, said first portion comprising a tubular body portion of said hat-shaped member, said second means sealing the interior of said tubular seal member comprising a flat end wall integrally joined to one end of said tubular -body portion of said hat-shaped member and said second portion comprises a ange of said hatshaped member integrally joined to and extending radially outwardly from said tubular body portion at the open end thereof, and wherein said iirst means clamps said seal member to said pump and comprises a wall of a housing containing an oil reservoir adapted to lubricate said drive means. n

14. In combination, a tubular seal member having a wall closing one end thereof and being open at the other end thereof axially opposite said one end thereof, a body having a chamber therein encircling said tubular seal member with a radial clearance therebetween, means clamping the open end of said tubular seal member in fixed sealed relation with said body, and motion transmitting means extending axially into said tubular seal member via the open end thereof and having means adapted to engage said tubular seal member adjacent said closed end thereof and to move with an eccentric motion in conjunction with such motion of said tubular seal member in the vicinity of said one end thereof, said tubular seal member being made orf a material adapted to permit flexure thereof radially of the axis of said tubular member between said fixed and closed ends of said tubular member.

1S. The combination set forth in claim 14 where said member comprises a tubular portion, said end wall being integrally joined to said tubular portion and closing one end thereof, a flange portion integrally joined to said tubular portion at said open end thereof disposed axially opposite said closed end thereof, said flange portion extending radially outwardly from said tubular portion, said member being made of material impervious to fluid and being flexible radially in said tubular portion between said ends thereof.

16. Apparatus for spraying liquid including in combination pump means including a pump chamber, a diaphragm having one side exposed to and forming a movable wall of said pump chamber, inlet means connected to said pump chamber and adapted for connection to a source of liquid to be sprayed, outlet means connected to said pump chamber, inlet and outlet check valve members disposed respectively in said inlet and outlet means and being cooperable with alternating exure of said dia- .phragm to pump the spray liquid from said inlet to said outlet means, a pulsing chamber filled with liquid, at least a portion of said diaphragm on a side thereof opposite said one side thereof being exposed to the liquid in said pulsing chamber, pulse means adapted to generate a pulsating pressure on the body of liquid in said pulsing cham-ber to produce said alternating liexure of said diaphragm, means forming a reservoir liquid `for receiving liquid from said pulsing chamber, first passage means connecting said reservoir to said pulsing chamber, valve means in said passage means for opening and closing communication between said pulsing chamber and said reservoir via said passage means, an output line connected to said outlet means of said pump, and means -for unloading said pump comprising means associated with said valve means operable to open said valve means in response to a predetermined pressure in said output line.

17. The combination set forth in claim 16 further including replenisher means cooperable with said pulse means including a second passage for admitting pulsing liquid from said reservoir to said pulsing chamber whereby the pulsing liquid recirculates via said pulsing charnber, said first passage means, said reservoir and said second passage means when said valve means is open.

18. The combination set forth in claim 16 wherein said unloading means includes means forming a pressure chamber communicating with said output line downstream o-f said outlet check valve member, a movable member disposed in said pressure chamber and movable in response to pressure of the liquid in said output line, a plunger operably connected for movement by said movable means and means biasing said plunger toward said pressure chamber, said biasing means yielding when said movable member is subjected to said predetermined pressure to thereby cause said plunger to open said valve means.

19. Means for reducing pressure in a uid pressure system having a chamber lcontaining liquid under pressure comprising casing means having a first bore extending therein and communicating with one end of said casing means, a valve seat in said lfrst bore, a check ball disposed in said first bore between said valve seat and said one end thereof, means fixed to said casing means between said check ball and said one end thereof adapted to limit movement of said check ball away from said seat, a

plunger slidably mounted in said casing means and having one end thereof projecting axially in said rst bore toward said check ball, said plunger being axially movable in said casing means such that said one end of said plunger is engageable with said check ball to hold the same 0E `said seat and is disengageable from said check ball to permit the same to seat against said seat, said casing means having a second bore adjacent the opposite end of said casing means, means sealing communication 'between said bores, a movable member disposed in said second bore and operably connected to said plunger, spring means connected between said casing means and said plunger for biasing said plunger toward said movable member, means adapted to connect said rst bore between said second bore and said check valve with said pressure chamber, and means adapted to connect said second bore between said movable member and said opposite end of said casing means with a source of liquid under pressure whereby the pressure of the source liquid acts on said movable member to control movement of said plunger to thereby release liquid from said pressure chamber |via said check ball in response to a given pressure of the source liquid.

References Cited UNITED STATES PATENTS 2,227,260 12/1940 Holveck et al 103-40 2,447,650 8/ 1948 Haumerson 103-40 2,681,750 6/1954 Booth 222-207 3,165,072 12/1965 Schultz 103-40 ROBERT B. REEVES, Primary Examiner.

HADD S. LANE, Assistant Examiner. 

